Gibney recalls how the Eagles co-founder and L.A. music legend, who died Jan. 18 at age 67, came up with the perfect line when helping Jackson Browne write lyrics to 'Take It Easy.'

I first met Glenn Frey when we initially talked about doing what became the film The History of the Eagles. I got on with him right away because he was forthright. He may have pissed off some people in his time, but it was often because he was brash and blunt. I liked that.

He was from Detroit, which was a blessing because it was a town of musical crosscurrents. He started in a band called The Subterraneans and ended up in the rock 'n' roll penthouse.

What to say about his legacy? He was part of one of the great rock 'n' roll stories — a duo (with Don Henley) in Linda Ronstadt's backup band that ends up putting together a group that records the best-selling album of the 20th century.

What I remember most was his work ethic. When it comes to music stories, the Amadeus myth is the biggest con. It suggests that some people are just born to genius. Bullshit. Charlie Parker didn’t just wake up one day, start to blow and watch his fingers play "Ornithology." He practiced. I remember Glenn talking to me about songwriting. He started out singing covers, and Bob Seger told him he had to start writing songs.

"But what if they’re bad?" asked Glenn. "Don’t worry," said Seger, "They will be. But they will get better."

When Glenn moved to L.A., he lived upstairs from Jackson Browne. He used to listen to him write songs on the piano, note by note, phrase by phrase, punctuated only by the occasional whistle of the tea kettle.

"Elbow grease." That always sounded to me like a term from the Motor City.

It turns out English poet Andrew Marvell — no auto mechanic — used it long before it got to Detroit. "Two or three brawny Fellows in a Corner, with meer Ink and Elbow-grease, do more Harm than an Hundred systematical Divines with their sweaty Preaching." When Marvell said "harm," he meant influence.

When Jackson Browne got stuck in writing "Take It Easy" on what to say after "Standing on a corner in Winslow, Arizona," he turned to Glenn Frey, who came up with, "It’s a girl, my lord, in a flatbed Ford …" Browne liked that — a rock haiku: "girl, lord, Ford …" Elbow grease. Hard work. And influence. Glenn Frey.

Gibney, an Oscar and Emmy-winning documentary filmmaker, produced the 2013 Showtime film History of the Eagles, which will re-air on the channel Jan. 19 at 8 p.m. ET/PT,Jan. 21 at 7:55 p.m. and Jan. 23 at 6:00 p.m.